The Pentagon has spent more than $31 billion purchasing approximately 26 million spare parts for its F-35 Lightning II stealth fighter fleet, but serious failures in inventory management and accountability have left millions of components difficult to track, raising concerns about aircraft readiness, financial losses and national security.
A new report released by the US Government Accountability Office (GAO) on November 9 found that the Department of Defense (DOD) has failed to establish adequate procedures to account for, monitor and verify F-35 spare parts distributed across a vast international supply and storage network.
The findings expose significant weaknesses in the Joint Strike Fighter (JSF) program’s logistics system, which relies on nearly 2,100 global suppliers and more than 700 government- and contractor-managed storage facilities. The network supports the production and maintenance of the world’s largest fleet of fifth-generation combat aircraft but has created substantial challenges for tracking the movement, ownership and condition of individual components.
According to the GAO, the Pentagon’s inability to maintain reliable records has already resulted in substantial financial losses. The F-35 Joint Program Office (JPO) has failed to establish the whereabouts of more than one million spare parts valued at approximately $85 million that went missing between 2018 and 2023.
More than three years after the GAO initially identified the problem, the Pentagon still cannot account for those components.
“As of March 2026, F-35 JPO did not know the status of lost F-35 parts valued at over $85 million that GAO reported on in 2023,” the report said.
The watchdog also found that the DOD continues to face difficulties accounting for government-owned components, including engines and aircraft tires, despite its responsibility to maintain complete and accurate property records.
“Although these are DOD-owned parts, DOD does not maintain complete records of the parts,” the report stated.
The problem is particularly significant because the F-35 program depends on an unusually extensive international production and sustainment network. Nearly 1,900 high-technology suppliers and approximately 1,000 small businesses participate in different parts of the supply chain, with companies spread across more than a dozen countries.
Spare parts are distributed among more than 700 storage locations, including facilities operated by government agencies, prime contractors and subcontractors. Components also move continuously between suppliers, maintenance facilities and storage sites.
While the international partnership allows participating countries to contribute their industrial capabilities and technological expertise, the GAO found that the resulting logistics network has become increasingly difficult for the Pentagon to oversee.
The central weakness is the absence of reliable, real-time information about where components are located, how many are available and who is responsible for them.
The GAO identified several weaknesses in the Pentagon’s system for recording and managing F-35 property.
The program’s Accountable Property System of Record (APSR), which is intended to provide an authoritative record of government-owned assets, contains inaccurate and incomplete information. Its records do not consistently reflect real-time changes in inventory, making it difficult to establish the actual status of spare parts.
The F-35 JPO has also failed to develop comprehensive procedures to validate the accuracy of information entered into the system.
Physical inventory procedures have proved similarly inadequate. According to the report, the Pentagon’s inspections have not consistently verified whether recorded parts actually exist or whether all government-owned components have been included in the inventory.
The problem extends beyond the accuracy of individual records. The GAO found that the locations of some subcontractor facilities holding F-35 components are unknown to the Pentagon. In addition, parts being transported between facilities can be excluded from inventory checks altogether.
Since 2020, the JPO has spent at least $17 million conducting physical inventories of F-35 assets across government- and contractor-managed facilities. However, those exercises have failed to establish the completeness and accuracy of the overall inventory.
Some contractor-provided data have also proved unreliable, further complicating efforts to reconcile government records with information maintained by private companies.
“Without accurate data in its APSR and properly executed inventory procedures for F-35 parts, DOD management will not have the information it needs to support warfighter readiness and reliable financial reporting,” the GAO warned.
The shortcomings also have implications for detecting fraud, waste and theft. Without procedures to systematically monitor and investigate missing components, the Pentagon cannot determine the full extent of inventory losses or establish whether individual incidents involve administrative failures, negligence or deliberate misconduct.
The inventory problems are particularly concerning because the F-35 fleet has already experienced persistent maintenance and mission-readiness difficulties.
Earlier this year, the GAO reported that the F-35’s mission-capable rate declined from 67 percent in fiscal year 2021 to 44 percent in fiscal year 2025. The mission-capable rate measures how frequently an aircraft is available to perform at least one assigned mission.
The fighter’s full mission-capable rate, which measures its ability to perform all assigned missions, fell even further, declining from 38 percent to 25 percent over the same period.
The latest report identifies unreliable spare-parts accounting as one factor contributing to the aircraft’s maintenance and availability challenges.
When the Pentagon cannot accurately determine which components are available, where they are stored or what condition they are in, maintenance organizations may struggle to identify the parts required to repair grounded aircraft.
Unreliable inventory information can also lead to unnecessary purchases, delays in maintenance operations and inefficient distribution of existing supplies.
“Accountability of these parts supports mission readiness and efficiency by providing management with information such as where parts are, who is responsible for them, and what condition they are in,” the GAO said.
In 2025, the Pentagon launched a $13.7 billion readiness improvement plan intended to increase aircraft availability by the end of the decade. However, the GAO’s findings suggest that improving maintenance performance will require more than additional funding.
Unless the DOD establishes effective inventory controls and ensures that spare parts can be located when needed, the F-35 program could continue to experience delays in repairs and persistent mission-capability problems.
The consequences extend beyond the fighter fleet. The GAO warned that the operational readiness of US forces depends on accurate information about the location, quantity and condition of military assets.
The accounting failures also compound the financial challenges facing the F-35, already described by the Pentagon as the most expensive weapon system in its history.
The program’s estimated life-cycle costs exceed $1.9 trillion, covering aircraft procurement, operations, maintenance and sustainment over several decades.
The more than $31 billion already spent purchasing approximately 26 million spare parts represents a substantial investment in keeping the global fleet operational.
However, the inability to account for millions of components raises questions about whether the Pentagon can effectively control the costs of maintaining the aircraft over its operational lifetime.
The GAO also linked the F-35 inventory problems to the DOD’s broader difficulties in passing its financial audits. Incomplete property records make it harder for the department to establish the accuracy of its financial statements and demonstrate that government-owned assets are properly accounted for.
The watchdog warned that unless the JPO introduces procedures to monitor losses, it will remain unable to determine their full extent or effectively prevent future incidents.
“Unless it implements procedures for monitoring losses, F-35 JPO will not know the full extent of losses of F-35 parts, and its ability to mitigate losses in the future will be decreased, reducing its ability to detect fraud, waste, or theft,” the report said.
The GAO recommended that the Pentagon develop specific procedures for monitoring missing F-35 components, calculate the financial value of lost parts, introduce specialized training for property managers and assess how many officials are required to oversee the program effectively.
The F-35 Joint Program Office said it agreed with the GAO’s recommendations and was taking steps to strengthen accountability across the program.
“To enhance accountability and mitigate the loss of F-35 parts, the department is implementing targeted actions to monitor and analyze loss trends,” a JPO spokesperson said.
The office is developing program-specific procedures and tailored training for Accountable Property Officers (APOs), alongside a detailed plan to define and structure the property-management program.
The JPO also said it was modernizing its inventory-management infrastructure by establishing direct, real-time data connections between government systems and those operated by prime contractors.
“The JPO is modernizing its property management infrastructure by establishing direct, real-time data interfaces between government and prime contractor systems. This integration directly addresses previous system gaps to ensure seamless accountability of F-35 spare parts,” the spokesperson added.
However, the scale of the existing problems means that implementing these changes across hundreds of facilities and thousands of suppliers could remain a significant challenge.
Beyond financial losses and aircraft readiness, weaknesses in the F-35 supply chain have also raised concerns about the security of sensitive military technology.
In September, reports emerged that a shipment of sensitive F-35 components sent from Australia to the United States had gone missing before resurfacing in Hong Kong.
The package reportedly included an aircraft canopy incorporating sensitive stealth technology. Its disappearance and subsequent appearance in a region under Beijing’s control raised concerns about whether China could potentially gain access to components associated with one of the world’s most advanced combat aircraft.
Although the incident does not establish that Chinese authorities obtained classified technology, it highlighted the potential security consequences of inadequate tracking procedures for sensitive military equipment.
The F-35 is currently the world’s most widely produced fifth-generation fighter, with more aircraft in service or production than the combined fleets of the US F-22 Raptor, Russia’s Su-57 and China’s J-20 and J-35A.
The United States operates the aircraft across all three military services: the Air Force, Navy and Marine Corps. It has also been exported to 18 countries, making effective international logistics and maintenance arrangements essential to sustaining the global fleet.
The program’s importance is expected to grow further following a framework agreement reached last month between the Pentagon and Lockheed Martin for the next decade of F-35 production and sustainment.
Under the proposed multiyear arrangement, Lockheed Martin is expected to produce 1,560 F-35 Lightning II fighters for US and international customers at a rate of 156 aircraft annually. The United States is expected to purchase at least 850 of them.
The agreement also covers associated initial spare parts, 10 years of modification kits and a sustainment package for the international F-35 fleet.
That expansion will increase the importance of maintaining a reliable supply chain capable of supporting aircraft across multiple countries and operational environments.
Ultimately, the GAO findings expose a fundamental weakness in the F-35 program: producing advanced stealth fighters is only one part of maintaining a combat-ready fleet. The Pentagon must also ensure that millions of components can be accurately accounted for, securely transported, properly stored and made available when required.
Without effective reforms, the nearly $2 trillion program risks continuing to face avoidable financial losses, maintenance delays and declining aircraft availability, potentially undermining the operational readiness that the F-35 was designed to deliver.
